Field of the Invention
The present invention relates to a photosensitive negative resin composition, in particular a photosensitive negative resin composition suitable for forming a fine structure by a photolithography process.
Description of the Related Art
As a fine processing technique, a photolithography technique is known in which a negative photosensitive resin is exposed and developed to form a structure (fine structure) having a fine pattern. This technique is widely used for, for example, applications of production of semiconductor integrated circuits, applications of production of masks for use in semiconductor exposure, applications of production of various MEMS (Micro Electro Mechanical Systems). As examples of the applications of production of MEMS, practical applications of this technique are being advanced in various compact sensors, microprobes, thin film magnetic heads, and ink jet recording heads.
As an apparatus for performing exposure, a stepper using the i-line as a light source has been widely used. In this technical field, it has recently been demanded to produce structures having more complicated and high-definition structures, and accordingly negative photosensitive resins have been desired which are capable of forming fine structures exhibiting high precision, under the action of light from a light source through a photomask. Examples of the high-definition structure include a nozzle ejection orifice of an ink jet recording head, wherein it is important to form the shape of the ejection orifice with good mask reproducibility.
As an example of the negative photosensitive resin, Japanese Patent Application Laid-Open No. 2008-256980 discloses a photosensitive resin composition including a polyfunctional epoxy resin and a cationic polymerization initiator.
Japanese Patent No. 3143307 discloses an ink jet head for production of MEMS including a nozzle ejecting an ink droplet by allowing bubbles generated by heating the heating resistor to communicate with the air outside. As the coating resin to be used for forming the ink flow-path wall of the ink jet head, there is disclosed a resin composition mainly composed of an epoxy resin solid at normal temperature.